Classical Music Library is a fully searchable classical music resource-a comprehensive database of distinguished classical recordings. It includes tens of thousands of licensed recordings that users can listen to over the Internet. The audio selections are cross-referenced to a database of supplementary reference information. Users browse, search, click, and then listen to the music through their headphones. More information here

Guide:

Technical Requirements for streaming audio files are listed here. Streaming the content of this database incurs no charge. Downloading for later play requires you to pay a fee.